1. Field of Invention
Cleaning method and apparatus.
2. Description of the Prior Art
For many years there has been a market demand for reclaimed bricks from buildings which have been torn down, as in urban renewal areas. Generally, the buildings are torn down by demolition charges which drop the entire building onto its original ground site, or the walls are broken apart and knocked down by the use of a swinging demolition ball or "skull cracker". In either case the impact forces break the walls into brick and motar agglomerations of various sizes incorporating a few or many bricks. Generally, many of the bricks ae freed or loosened somewhat from the agglomeration by the impact of the mass when it is struck by the ball or when it strikes the ground or rubble on the landsite upon falling. The bricks remaining agglomerated can be broken free from the mass readily, but the original mortar usually adheres to all or some of the faces of the freed bricks, as initially obtained at the worksite. Usually the mortar adheres in patches of indiscriminate sizes and heterogeneous array, ranging from patches which cover all of the one or more faces to occasional small isolated patches on one or more faces. To reclaim or salvage such bricks for reuse, substantially all of the mortar must be removed without abrading, scratching, or damaging the original faces of the bricks, thus leaving thereon, at most, superificial films or patches of discoloration where some of the mortar has penetrated into the pores and interstices opening in the brick faces.
At present this mortar is removed manually by chisel type tools and hammers. At times, the mortar on the faces is subjected to rotary abrading discs, or power driven belts as the main or final step in cleaning. Reclaiming the bricks by chisels is a rather slow and expensive procedure, largely because the forces applied to the mortar to dislodge the layers thereof, or to reduce its thickness, are highly concentrated or localized sharp impacts, and are often applied to mortar on one face while the opposite face is unbuttressed. Therefore, such forces impose on the brick chipping and bending stresses which often disfigure or fracture the brick or break it apart. Frequently this occurs after much of the mortar has been removed, and as a result the cleaning work already effected is wasted. A further disadvantage in mortar removal in this manner, especially near the brick edges and corners, is localized fracturing and chipping off the such large flakes or chunks that the underlying brick material, with its darker appearance, is exposed, giving a sharp undersirable mottled appearance to the surface or destroying the original geometric shape of the brick. Rotary abrasive discs and belts are very expensive and do not cause the layer of mortar to break free. Instead, the layer must be removed solely by abrading action. As a result, the original brick surface is generally not exposed but carries coextensive thin strata of mortar. Often grinding exposes a new surface as a result of removing a thin strata of the brick material itself. Thus the attractive surface appearance characteristics of used bricks is destroyed.